1. Field of the Invention
The present invention relates to electronic equipment operable with a memory card in or out of which image data or similar data may be written or read and, more particularly, to a memory card control device built in such equipment.
2. Description of the Related Art
Electronic equipment operable with a memory card include an electronic still camera capable of picking up a desired scene and generating image data representative of the scene. It is a common practice with this kind of camera to install a memory card control device for controlling the writing or reading of image data in or out of a memory card removably mounted on the camera. A memory card writes or reads image data under the control of the memory card control device which may be constructed into an LSI (Large-Scale Integrated circuit). With this configuration, it is possible to connect a memory card to the camera and store image data generated by the camera in the card. It has been customary with a memory card to assign a supply voltage of 5 volts for operation. However, advanced semiconductor technologies have realized memory devices operable at a supply voltage of 3 volts although operating at the same timing as memory devices whose rated supply voltage is 5 volts. A memory card using such an alternative memory device is, of course, driven by a voltage of 3 volts.
The conventional memory control device has the following problem when it comes to control over memory cards each having a particular rated supply voltage. Electronic equipment has customarily been constructed to assign to a memory card control device thereof a predetermined supply voltage matching a memory card for use therewith. A memory card implemented as an LSI, for example, has to be provided with the same supply voltage as signal input/output (I/O) pins. Hence, the control device cannot control both of the 3-volt and 5-volt memory cards unless the supply voltages for the LSI and surrounding circuitry are changed each time in conformity to the supply voltage of the memory card. It follows that to change the supply voltage of the control device, the entire equipment has to be initialized by resetting or similar sequence control. With the conventional control device, therefore, it is difficult to construct electronic equipment operable with various kinds of memory cards each having a particular rated supply voltage.